A conventional CC driving system employed in an active-matrix liquid crystal display device is disclosed in for example Patent Literature 1. The following description discusses the CC driving by taking as an example the disclosure in Patent Literature 1.
FIG. 23 illustrates a configuration of a device that realizes the CC driving. FIG. 24 illustrates operating waveforms of various signals in CC driving carried out by the device shown in FIG. 23.
As illustrated in FIG. 23, a liquid crystal display device that carries out the CC driving includes an image display section 110, a source line driving circuit 111, gate line driving circuits 112, and CS bus line driving circuits 113.
The image display section 110 includes a plurality of source lines (signal lines) 101, a plurality of gate lines (scanning lines) 102, switching elements 103, pixel electrodes 104, CS (Capacity Storage) bus lines (common electrode lines) 105, retention capacitors 106, liquid crystals 107, and a counter electrode 109. The switching elements 103 are provided in the vicinities of respective intersections of the source lines 101 and the gate lines 102. The switching elements 103 are connected with the respective pixel electrodes 104.
The CS bus lines 105 are arranged in parallel with the gate lines 102 such that each of the CS bus lines 105 is paired with a corresponding gate line 102. Each of the retention capacitors 106 has one end connected with a pixel electrode 104 and the other end connected with a CS bus line 105. The counter electrode 109 is arranged so as to face the pixel electrodes 104 via the liquid crystals 107.
The source line driving circuit 111 is provided to drive the source lines 101, and the gate line driving circuits 112 are provided to drive the gate lines 102. The CS bus line driving circuits 113 are provided to drive the CS bus lines 105.
The switching elements 103 are formed by amorphous silicon (a-Si), polycrystalline polysilicon (p-Si), monocrystalline silicon (c-Si), or the like. Because of the structure of the switching elements 103, a capacitor 108 is formed between a gate and a drain of each of the switching elements 103. This capacitor 108 causes a phenomenon in which a gate pulse from a gate line 102 causes the electric potential of a pixel electrode 104 to shift toward a negative side.
As shown in FIG. 24, in the liquid crystal display device, the electric potential Vg of a gate line 102 is Von only during an H period (horizontal scanning period) in which the gate line 102 is being selected. The electric potential Vg is retained at Voff during the other periods. The electric potential Vs of a source line 101 has a waveform whose amplitude varies depending on a video signal to be displayed, but its polarity is identical for all pixels in an identical row and is reversed every one (1) row (one horizontal, scanning period) (one-line (1H) reversal driving). Note here that, since it is assumed in FIG. 24 that a uniform video signal is supplied, the amplitude of the electric potential Vs is constant.
The electric potential Vd of a pixel electrode 104 is equal to the electric potential Vs of the source line 101 during a period in which the electric potential Vg is Von, because a switching element 103 is conductive. Then, at the moment the voltage Vg becomes Voff, the electric potential Vd slightly shifts toward a negative side via a gate-drain capacitor 108.
The electric potential Vc of a CS bus line 105 is Ve+during an H period in which a corresponding gate line 102 is selected and in the next H period. The electric potential Vc is switched to Ve− during the H period after the next, and is retained at Ve− until the next field. This causes the electric potential Vd to be shifted toward a negative side via a retention capacitor 106.
As a result, the electric potential Vd changes with larger amplitude than the electric potential Vs. This makes it possible to further reduce the amplitude of change in the electric potential Vs. Accordingly, it is possible to simplify a circuit configuration and reduce power consumption in the source line driving circuit 111.